Re: [External] : Undefined behavior for the function ‘last’ or an error?

[tpeplt <tpeplt@gmail.com>]

Drew Adams <drew.adams@oracle.com> writes:

>
> IMO this should be fixed.  Someone(TM) will
> maybe say it's intentional (but then it
> should be doc'd).
>

Also, if it is intentional, then it should be documented why it is
inconsistent with how the related functions ‘butlast’ and ‘nbutlast’
behave so that users do not expect those two functions to accept
non-lists as an argument.

Also, checking a few other list functions, ‘nthcdr’, ‘take’, and
‘ntake’, there is a similar inconsistent result that might be
intentional or not.  The behavior of ‘nthcdr’ is unexpected, while the
behavior of ‘take’ and ‘ntake’ are unpredictable because these are
Emacs-Lisp-specific functions.

(nthcdr 0 'a) => a

(nthcdr 1 'a) => a
*** Eval error ***  Wrong type argument: listp, a

(take 0 'a) => nil

(take 1 'a) => nil
*** Eval error ***  Wrong type argument: listp, a

(ntake 0 'a) => nil

(ntake 1 'a) => nil
*** Eval error ***  Wrong type argument: listp, a

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